1. Field of the Invention
This invention relates to a novel and improved structure for supporting tubes which are subjected to the heat of a furnace, and more particularly to a tube support structure for preventing the tubes from exceeding their bending moment and becoming distorted during superheating of a fluid passing therethrough. While the invention will be ordinarily useful as a tube support in all types of fluid superheating operations, the invention is particularly useful in superheating steam for the purpose of supplying heat required for chemical reactions such as in the formation of styrene.
2. Brief Description of the Prior Art
U.S. Pat. No. 1,896,176, Feb. 7, 1933 discloses a means for supporting tubes which are subjected to the heat of a furnace and for preventing the distortion of the tubes. In accordance with the patent, the portions of the tubes which are exposed to the radiant heat of the furnace are left free to expand inwardly as they become heated. Additionally, struts are abutted against the tubes so that outward movement of the tubes is prevented.
U.S. Pat. No. 1,941,258, Dec. 26, 1933 discloses a superheater in which substantially parallel co-planar pipe lengths include means exterior thereto for connecting an adjacent pair of pipe lengths together, the connecting means including a slidable interlocking joint so as to permit relative motion of adjacent pipe lengths in the longitudinal direction during periods of changing temperatures in the boiler.
U.S. Pat. No. 2,439,067, Apr. 6, 1948 relates to devices for supporting piping systems against vibration and shock while at the same time permitting automatic adjustment of the position of the pipe to accomodate thermal expansion or other normal and necessary relative movement between the piping and its support. An elaborate system is devised including a movably mounted truck which is adapted to roll and which supports a spring mounted hanger and lengths of piping.
U.S. Pat. No. 3,760,774, Sept. 25, 1973 and British Pat. No. 1,409,943 disclose boilers which include furnace walls which are designed to withstand the pressures and thermal changes within the furnace and which include means by which the forces exerted on the walls may be transmitted to a flexible framework.
U.S. Pat. No. 1,990,058, Feb. 5, 1935 discloses a support structure for superheaters.
While the prior art structures may have been somewhat successful in preventing the distortion of superheater tubes during the thermal expansion and contraction thereof caused by thermal changes taking place in the furnace, prior art tube support structures have been cumbersome to install and in view of the complexity of design or use of a relatively large number of connecting components difficult to maintain in the proper operating orientation. Further still, tube support structure which is mounted in the interior of the furnace is also subjected to the thermal changes taking place, and thus often becomes distorted, thereby reducing it usefulness.
Accordingly, it is a primary object of the present invention to provide a supporting arrangement for superheater units which will prevent the individual superheater tubes from exceeding their bending moment and becoming distorted in the environment of a furnace and yet shall be convenient and economical to install and maintain.